Increasing PSRR in close-op and bandgap

[rambus_ddr]

I am designing a close- op and bandgap, the PSRR always is very low only 60dB, But the Spec need meet 70dB. In order to increase the PSRR, I don't use Miller compensation, the capacitor are connect ground direct. Since the power voltage is 3.0V , so i can't use cascode. Who can give any devices or papers. Thanks!

 

[uladz55]

Re: Let's discuss PSRR

Hi,

check this paper

**broken link removed**

 

[Humungus]

Re: Let's discuss PSRR

PSRR is linked to output conductance of transistors as well as matching among them. Try to increase channel length of your current mirrors and increase the area of transistors in general to improve matching.

Also, actually it depends on the Vth of your transistors, 3V is high enough to accomodate cascodes. Miller compensation could also help.

 

[andy2000a]

Re: Let's discuss PSRR

for bandgap design .. we usually use cascode current mirror ..
but cascode can improve PSRR .. but can not work on low power supply ..

if your Power supply > 3.3v I think you can cascode 3 stage mos
and use "wild swing" cascode improve PSRR

 

[lunren]

Re: Let's discuss PSRR

if your Power supply > 3.3v I think you can cascode 3 stage mos
and use "wild swing" cascode improve PSRR

What is the "wild swing" cascode?